A new class of X-ray optic will be developed that can be used with conventional mammography X-ray tubes, in place of K-edge filters, in order to produce a mono-energetic X-ray beam. The X-ray optic is based on proven, currently-available technology, comprising planar reflective multilayer X-ray mirrors that act as extremely efficient energy filters. The multilayer mirror coatings are designed to have a narrow energy bandpass, and can be tuned arbitrarily during fabrication to specific X-ray energies. The mirror reflectance at the target energy is high, while the reflectance outside of the narrow bandpass is orders of magnitude smaller. The X-ray optic to be developed, when used in place of K-edge filters either in a scanning slot or full-field geometry, and in combination with conventional mammography X-ray tubes, will result in a significant improvement in image quality while simultaneously reducing patient dose, especially in the case of thicker, more dense breasts, and without any increase in exposure time or degradation of spatial resolution. These expected performance enhancements represent important clinical benefits that will facilitate more accurate and sensitive detection of small lesions, thereby improving the health of a substantial portion of the human population. Building upon the successful demonstration of the technical feasibility of this technology achieved during Phase I, this technology will be fully developed during Phase II for incorporation into commercial analog or digital mammography machines.Project Narrative [unreadable] [unreadable] We plan to develop a new class of X-ray optic for mammography that will result in a significant improvement in image quality while simultaneously reducing patient dose. These expected performance enhancements represent important clinical benefits that will facilitate more accurate and sensitive detection of small lesions, thereby improving the health of a substantial portion of the human population. We plan to incorporate the technology we develop into commercial analog and/or digital mammography machines. [unreadable] [unreadable] [unreadable]